Gear assemblies for agricultural work vehicles are known from the prior art, for example for tractors or harvesting machines, the gear assemblies having a gear system implemented by a plurality of gear units arranged in succession. Such gear assemblies are used to meet the high demands required by a gear spread which is as sensitive and as extensive as possible, as is required in agricultural work vehicles. Moreover, for the same reasons, such gear assemblies are also used in the field of construction machines.
EP 1624232 A1 discloses a gear assembly for a work vehicle comprising a plurality of gear units arranged in succession. A first gear unit is configured as a reverse gear and connected to a second gear unit. The second gear unit has an input shaft connected to a distributor stage and an output shaft. Moreover, two layshafts are provided in the second gear unit. The layshafts are driven via the distributor stage. By way of toothed wheel pairs, which are arranged by way of toothed wheels on the layshafts and the output shaft, the output shaft may be driven with different gear stages. The output shaft of the second gear unit is connected to a third gear unit. The third gear unit represents a secondary transmission and permits a further staging of the gear stages selected in the second gear unit. The disclosed gear assembly is designed to permit advantageous gear shifts at a relatively low construction cost, where there is a corresponding total gear spread. The selected design which is additionally required by the type of gear units selected, however, has only a low degree of compactness and variability, namely based on the selected construction, possibilities for variation relative to predetermined and/or selected maximum or minimum output speeds only being able to be implemented with difficulty and only with a relative high structural cost and a high number of different parts. In this regard, for example, the axial distance of at least one layshaft has to be altered, which requires further structural measures, such as the adaptation of shift forks, etc. The same applies to possibilities for increasing and adapting the power spectrum predetermined by the gear assembly, as well as possibilities for combining with additional or auxiliary drives.
A further drawback is that both the design of the gear assembly disclosed in EP 1624232 A1 and the design of other known gear assemblies of the aforementioned type, have an irregular path of the efficiency and/or power loss which is associated with high vibrations, depending on the rotational speed and/or driving speed of the respective vehicle, which is a drawback for implementing an automatic gear system, in particular when applying driving strategies with regard to optimized fuel consumption, as such paths which are irregular and/or associated with vibrations, may rapidly result in oscillation shifts. Moreover, such a gear assembly is also only suitable for use in an agricultural machine to a limited extent, such as for example in a tractor, as a power take-off shaft may only be connected indirectly to the input shaft of the gear assembly.